1. Field of the Invention
The invention relates to a Coriolis mass flow meter comprising at least two curved measurement tubes, at least one actuator arrangement, at least one sensor arrangement and comprising at least one housing structure, the measurement tubes being combined on the inlet side and the outlet side with at least a first oscillation node plate and a second oscillation node plate.
2. Description of Related Art
Mass flow meters which operate according to the Coriolis principle are known in a multiplicity of configurations in the prior art. Coriolis mass flow meters make it possible to determine the mass throughput of the medium flowing through the measurement tube with high accuracy. In order to determine the mass throughput, the measurement tube is excited into oscillations—in particular, with the eigenfrequency of a particular eigenmode of an oscillation—with an oscillation generator or a plurality of oscillation generators, and the oscillations actually resulting are recorded by oscillation pick-ups and evaluated. The actuator arrangement for the oscillation generation and the sensor arrangements for the oscillation recording are generally constructed so that they comprise a permanent magnet and a magnetic coil for electrically transmitting oscillations to the measurement tube and recording oscillations of the measurement tube, respectively, although the specific configuration is not important here.
In order to evaluate and determine the mass throughput, the phase shift between the oscillations of different sections of the measurement tubes, respectively recorded by two sensor arrangements, is determined, this phase shift being a direct measure of the mass throughput. Coriolis mass flow meters which have a single measurement tube have been known for many years, as well as those which have precisely two or four measurement tubes, the measurement tubes being either essentially straight or curved.
The accuracy with which the mass throughput can be recorded depends, inter alia, on whether perturbing oscillations are superimposed on the oscillations recorded by the sensor arrangements. In order to move undesired oscillation modes as far as possible away from the working frequency of the Coriolis mass flow meter, the oscillation properties of the measurement tube arrangement are modified by design, for example, by modifying the flexural stiffness of individual components, so that no perturbing oscillations occur in the immediate vicinity of the working frequency of the Coriolis mass flow meter.